Method of forming duplexed webs



June 20, 1939; I CLAXTON AL 2,163,372

METHOD OF FORMING DUPLEXED was Filed (kit. 20. 1936 I W Rad 1 mo v WW Patented June '20, 1939 "UNITED STATES 2,163,372 METHOD or FORMING DUPLEXED Edmund Claxton and He WEBS rbert Paschke, Lancaster,

Pa., assignors to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania Application October 20,

9 Claims.

also selected as to quality and color and are 1 applied to a web of tissue paper, usually of the Japanese silk variety; which has previously been coated with a suitable adhesive. Various types of varnishes are generally usedfor this purpose. The sheets are positioned by hand with-the edges in abutting engagement so as to. completely cover the tissue web. The duplexed web is subsequently slit into the desired widths and rolled into bobbins for use in. tipping machines. The other process is similar except that instead of cutting a multiplicity of separate sheets from individual blocks, the blocks are adhesively joined and secured to-tlieperiphery of a rotatable wheel or drum and present a subtantially continuous surface which is engaged by a veneering knife which severs a thin continuous web of cork from the blocks. The cork web is of the desired thickness and is composed of a plurality of thin sheets of cork adhe'sively joined at their abutting edges. This sheet is subsequently duplexed wltha tissueeweb'in much the same manner as the individual sheets above described, a varnish or boiled oil type of adhesive being generally employed.

' Natural cork is characterized by a multiplic- I ity of natural openings extending through aLmaterial portion of the thickness of the cork bark. It is essential, therefore, that only the highest quality corkwood, as free-as possible'from' such openings, be selected'for tipping purposes. The frequency and size of thenatural openings isone of the factors determining the quality of the cork for tipping purposes. Generally stated, only the soft, velvety and less porous sheets are used, the opemharsh material beingdiscarded. The supply of suitable quality .corkwood for this purpose is quite limited. Evenwith the most careful selection, the natural cork when out to the thickness used for tipping will contain natural. openings. This necessitates that the duplexing adhesive be carefully selected and the quantity 1936, Serial No. 106,639

applied be accurately limited in order to prevent exudation of the adhesive through the pores of the cork and, upon rolling, adhesive securement of the adjacent convolutions of the duplexed web, causing a shut-down of the tipping machine to which such bobbin is being fed. There is always present the problem of preventlng gumming of the cutting knife by exuded adhesive. When it isconsidered that the knife must sever a. sheet about .0025" thick, the keenness of the knife edge and the smoothness of its surface are important and any foreign matter disposed on the knife will impair its cutting qualities.

In the copending application of Herbert Paschke, filed October .20, 1936, Serial No. 106,640, a tipping material isprovided in which the facing layer is formed of a cork agglomerate. Thiseliminates many of the problems incident =to the use of natural cork blocksvas the base material, and our invention is applicable to themanufacture of tipping material includinga cork composition facing web.

In the copending' application of Harry H. Straus, filed October 20, 1936, Serial Number 106,666, a method and apparatus is disclosed wherein the tissue sheet is adhesively joined to the natural cork blocks or a composition cork block as it rotates, and, upon subsequent cutting, a unitary laminated article is formed having a facing of cork or cork composition and a reenforcing web of tissue. adhesively secured thereto. Our method may be practiced'by utilizing individual sheets of natural cork severed from individual blocks; by utilizing continuous webs of either natural or composition cork, or by. operating directly against ,a cork body applied to a wheel as disclosed in the Straus application above referred to. s Our method contemplates the use of a thermoadhesive material which is preferably capable of being activated by the application of a mild degreev of heat, insufficient to deleteriously afiect the cork. The adhesive, in our preferred embodiment, is preferably applied to the supporting and strengthening tissue and is dried or hardened. This divorces the adhesive applying operation from the duplexing operation and permits careful control of the amount of adhesive applied, and the speed of drying or hardening of theadhesive does notin any manner affect the speed of cutting when a continuous process is used. 7 A suitable thermo-adhesive may be continuous- 7 1y applied to the cork surface prior to the applica tion of the tissue and heat activation accomplished to secure the tissue to the periphery of the cork wheel prior to severance of the cork sheet therefrom, or such adhesive may be applied to the tissue, and while still in a liquid or tacky state urged into engagement with the cork surface and thereafter heat activated.

According to our preferred embodiment, the tissue is first coated with a thermoplastic adhesive, dried and formed into, rolls. The web is preferably the-same as the width of the cork to be duplexed thereto. Since the tissue is, in the final product, adhesively secured to the cigarette paper from which the cigarette is formed,

it is desirable to provide duplexing adhesive which will not penetrate the tissue to such an extent as to prevent proper. adhesion of the tipping material with the cigarette paper.

We have found a vinyl resin adhesive embodying the following ingredients:

. Part Resin of 80-160 C. softening point 1 Ethyl alcohol 1 to be especially well suited for our purpose since it is rendered thermoplastic and adhesive by the application of about 100C. of heat, is substantially tasteless and odorless, light colored and sets up rapidly after heat ceases to be applied. Glueglyceri'ne types of adhesive, cellulose ester, modi-' fied protein or other similar thermoplastic or thermosetting adhesives will be found useful in carrying out our method. If desired insolubilizing agents such as paraformaldehyde may be used with the protein type adhesives and may be conveniently applied by dusting the same on the cork or tissue prior to activation of the adhesive. If glue-glycerine be used, the adhesive may be formed of equal parts by weight of glue, glycerine and water and may be applied from a steam jacketed trough having a heated applicator roll. Such mixture will be suitable for application when heated to about 100 C. The glycerine may be replaced, wholly or in part, by glucose, invert sugar, sorbitol or similar plasticizing agents. Resinous type adhesives other than the vinyl resin above described may be used, provided their melting points are not excessively high.

The materials to be duplexed are placed in juxtaposition with the adhesive disposed therebetween and heat activation thereof is effected. With some types of adhesives it will be found desirable to hold the tissue and cork under pressure until the adhesive has set, at least sufllciently to permit handling without disrupting the adhesive bond. The degree of heat to be applied, the heating period and the cooling period, if any, will depend, to some extent at least, upon the type of the adhesive used, and the materials to be duplexed.

A mechanism suitable for carrying out our method is shown diagrammatically in the accompanying drawing. In the drawing there is illustrated a plurality of natural cork blocks 2, ad-

'hesively secured at their abutting edges 3, positioned on a rotatable wheel 4' moving in the direction of the arrow. A roll 5 of tissue having a dried adhesive coating on its under surface 6 is positioned for feeding to the periphery of the blocks disposed on the wheel. Pressure rolls 1 which are suitably heated, as by electricity as shown in the drawing, press the tissue 5 into engagement with the cork surface and activate the dried coating, securing the tissue to the cork surface. Aplurality of pressure rolls 8 may be provided to press the tissue into firm engagement with the cork surface after heat has been applied. A rotating knife 9 is brought into operative engagement with the cork 2 and severs a continuous strip l therefrom. The tissue is continuously fed upon rotation of the wheel 4 and the strip' I0 is formed of indefinite length/ and has the tissue 5 adhesively joined thereto. The mechanism for rotating the wheel 4 and knife 5 and for imparting progressive translatory movement between the knife and the cork to be out has not been shown. Cork veneering machines are well known to those skilled in this art.

The outside diameter of the wheel may be 48" and the speed of rotation about 10 revolutions per minute or a peripheral travel of about 125 feet per minute which, with about 8 feet of total working circumference of cork, provides approximately four seconds time for activation of the adhesive. The advantage of our method under such conditions is immediately apparent. Another advantage derived from the use of a dried, thermoplastic adhesive is that it eliminates any solvent penetration which might soften the cork. It should be remembered that the cork sheet to be cut is but about .0025" thick and any material softening thereof will render proper cutting difflcult.

Another problem, which has been successfully solved by this invention, was that of breakage of the thin web of cork as it was severed by the cutting knife. By our method, the reenforcing tissue is applied and the adhesive activated prior to cutting and the cork sheet is adequately strengthened. This permits higher operating speeds and, where desired, lower quality cork, which would not possess sumcient strength to permit cutting and handling by prior methods, may now be utilized with good results.

In carrying out our method with the use of in dividual cork sheets, or previously cut cork paper, assembly may be effected more readily than by prior methods since the adhesive will be dry and will facilitate positioning of the sheets as contrasted with the use of wet, tacky adhesives which would not permit of movement of the cork sheet when once brought into engagement therewith. With our method the positioning may be effected and the materials to be duplexed passed over a heated platen to effect activation of the adhesive. Pressure will be required with most adhesives to secure proper engagement of the laminating materials and pressure rolls may be utilized for that purpose. If desired, the dried coating may be rendered slightly tacky before the laminating sheets or web is applied.

Sanding of the cork surface may be carried out in the same manner as heretofore. The sanding operation may be carried out as a continuation of the duplexing and cutting operations if our preferred method be employed.

By the method of this invention the attainment of higher production speeds will be facilitated and a higher quality, more uniform product will result.

While we have illustrated and described certain specific embodiments of our invention it will be understood that the invention may be otherwise embodied and practiced within the scope of the following claims.

We claim:

1. In the method of forming duplexed webs of indefinite length, the steps consisting in applying a ribbon of duplexing material carrying a dried, protein type thermo-adhesive coating to the pehesive and insolubilizing the same by the application of heat thereto, and severing said body at the periphery thereof with a rotating cutting edge to form a unitary, duplexed web.

2. In the method of forming duplexed webs,

the steps consisting in feeding a web of duplexing material of tissue thinness to substantially the entire width of the peripheral surface of a rotating body of cork with a thermally activatable adhesive disposed between the duplexing web and the peripheral surface of the body, ap-

plying heat to the adhesive and pressure between the web and the peripheral surface of the body to activate the adhesive and permanently join the web to the peripheral surface of the body, and

severing the cork body continuously at a depth in the order of .0030" from the periphery thereof with a rotating cutting edge while imparting progressive translatory motion between the cutting edge and the body, said severance being effected at a point removed from the point of application of the web to the body so that the duplexing web serves to reenforce the cork ribbon at the point of severance from the body to obviate rupture thereof.

3. In the method of forming duplexed webs, the steps consisting in feeding a web of duplexing material of tissue thinness carrying a dried, thermally activatable, latently adhesive coating to substantially the entire width of the peripheral 5 surface of a rotating body of cork, activating said adhesive while applying pressure between the web and the peripheral surface of the body to permanently join the web to the peripheral surface of the body and severing the cork body continuously 40 at a depth in the order of .0030" from the periphery thereof with a rotating cutting edge while imparting progressive translatory motion between the cutting edge and the body, said severance being efiected at a point removed from the point 45 of application of the web to the body so that the duplexed web serves to reenforce the cork ribbon at the point of severance from the body to obviate rupture thereof.

4. In the method of forming cork cigarette tip- 50 ping material, the steps. consisting in coating 9.

web of tissue paper with a thermoplastic adhesive,

feeding said web to the peripheral surface of a rotating body of cork, maintaining said web in engagement with the peripheral surface of the 55 body until the adhesive has set sufficiently to prevent dislodgment of the tissue therefrom and conto the body so that the duplexing web serves to reenforce the cork ribbon at the point of severance from the body to obviate rupture thereof.

5. In the method of forming a duplexed web, the steps consisting in coating a web of thin tissue paper with athermo-setting adhesive, said adhesive coating penetrating said paper through a portion only of its thickness, drying said coating, feeding said web to the peripheral surface of a rotating body of cork being severed by a rotating cutting edge into a thin ribbon in the order of .0030" thick, and activating said dried adhesive by applying heat and pressurethereto to secure the web to the periphery of the cork body at a point removed from the point of severance so as to form a duplexed web upon continued severance of the body.

6. The method of forming duplexed webs as recited in claim 2 in which severance of the'cork is eflected prior to any material softening thereof caused by penetration of the adhesive into the cork body. I

'7. In the method of forming duplexed webs, the. steps consisting in feeding a web of tissue paper to the peripheral surface of a rotating body of natural cork having ports extending inwardly from the peripheral surface thereof, said paper carrying a thin coating of dried thermoplastic adhesive, activating said adhesive by the application of heat thereto, cooling said coating to render said adhesive sufliciently hard to be nongumming, whereby any adhesive material which becomes disposed in the pores of the natural cork will not deleteriously affect the cutting operation, and severing the cork body continuously at a depth in the order of .0030" from the periphery of the body with a rotating cutting edge.

8. A method in accordance with claim 7 in which the adhesive is of such character and the activation is carried out by the steps of heating and subsequently cooling so that the adhesive does not penetrate the pores of the natural cork to a adhesive coating is formed of vinyl ester.

EDMUND CLAX'ION.

'1 EABCHKE. 

